In my opinion it’s not a good alternative if you or your team members expect exactly the same quality of service. When you switch to Nextcloud you’ll have to expect more bugs, less reliability, less performance and obviously more maintenance (since it's typically self-hosted) compared to Google Drive, Dropbox or One Drive. So you'll have to go into this with a different kind of mindset. What you gain is independence, privacy and extendability due to a rather big platform ecosystem.

E.g. here are some specific things and examples of things you'll have to deal with, in no specific order. These are just some things I've had to deal with recently.

- You'll have to educate people in your group that there are at least 3 different ways to share files among each other and that they can all coexist in parallel (Individual Shares vs. Group Shares vs. Group folders vs. Circles/Teams) (I did a german blog post on this: https://bitbetter.de/blog/nextcloud-freigabe-chaos/)

- Handling of file/folder names with special characters is a mess e.g. if you have Windows and Linux clients there will most certainly be conflicts. (Luckily this has been fixed recently by the `forbidden_filename_characters` config option – which is not enforced yet via the Web UI) see https://github.com/nextcloud/ios/issues/2802

- Creating Nextcloud users with spaces in their names, will break CalDAV on iOS Devices (https://github.com/nextcloud/server/issues/15641)

- Nextcloud (aka Collabora) Office is very slow if you want to actually work collaboratively with it (no matter the power of your Collabora server) – unfortunately it's no match for Google Docs or Office 365

Don't get me wrong: It's still a fantastic Open Source project with tons of talented people and it's a beacon of hope in the GAFA world. Everyone should try it out (and help it evolve) so it can be better than the commercial alternatives. But going into this and expecting to get the same kind of product quality like Google Drive/One Drive/Dropbox will lead to disappointment.